Dr. rer. nat. Hans-Gregor Hübl

Lehrveranstaltungen und Termine

Ausgeschriebene Angebote für Abschlussarbeiten

Electron spin dynamics in a strong coupling environment

Modern quantum circuits allow to study strong light-matter interaction in a variety of systems. This so-called strong-coupling regime requires that the coupling strength between the two subsystems exceeds their individual loss rates, rendering superconducting microwave resonators ideal due to their vanishingly low resistance. For this project, we use a paramagnetic spin ensemble of phosphorus donors in a silicon host as second system, as they show coherence and life-time in the order of seconds and minutes, respectively. The goal of this project is develop implement and develop pulse sequences to coherently control the spin ensemble and investigate the response of the coupled system.

We are looking for a highly motivated master student joining this project. The goal of your thesis is the implementation and development of adiabatic and optimal control pulse sequences for the investigation of the coherent dynamic of the coupled spin microwave system. Additionally, as microwave resonators play a vital role for the project, you will improve and tailor the existing microwave resonators for the specific needs of the project. The main goals of the project require simulation of the microwave circuits using finite element modelling, programming skills for the implementation of the pulse sequences and state of the art nano-fabrication techniques. 

geeignet als

• Masterarbeit Physik der kondensierten Materie
• Masterarbeit Applied and Engineering Physics

Themensteller(in): Hans-Gregor Hübl

Elektrisch gesteuerter Magnontransport in magnetisch geordneten Isolatoren

Angular momentum transport in magnetically ordered insulators is carried by magnetic excitation quanta in contrast to magnetic conductors, where mobile charge carrier also carry angular momentum. In magnetically ordered insulator/normal metal hybrids it is possible to study the transport of angular momentum by all-electrical means via the spin Hall and inverse spin Hall effect in the normal metal. The focus of this project is the investigation of possibilities to manipulate the angular momentum transport in the magnetically ordered insulator by electrical means and by finite size effects. In addition, another goal is the enhancement of the sensitivity of the currently existing measurement setup and the realization of new measurement protocols in hard- and software.

An ambitious master student with good analytical skills is required to carry out these experiments on all-electrical magnon transport. One part of the thesis is the fabrication of nanometer sized devices for the experiments via electron beam lithography and UHV sputtering. The properties of these devices will be analyzed using magnetotransport experiments in superconducting magnet cryostats. Another important aspect is the realization of more sophisticated measurement methods, aiming for a enhancement in sensitivity, a better signal-to-noise ratios and a higher versatility of the measurement protocols

geeignet als

• Masterarbeit Physik der kondensierten Materie
• Masterarbeit Applied and Engineering Physics

Themensteller(in): Rudolf Gross

Nano-strings excited by magnetic torques

Nano-mechanical beams are prototype harmonic oscillators, and can be straightforwardly integrated with other nanoscale systems. For example, coupling nano-beams to coplanar microwave cavities yields so-called hybrid electro-mechanical systems with intriguing properties, e.g., electro-mechanically induced transparency. In a similar fashion, ferromagnetic nanostructures can be integrated with nano-beams. This enables the design and the investigation of spin-phonon coupling down to the single excitation level, or nanoscale Einstein-de Haas experiments, in which the angular momentum change arising from magnetization reversal is transferred into a mechanical vibration of the beam. 

We are looking for a motivated master student for a magnetic nano-beam oriented master thesis. The goal of your project is to investigate the static and dynamic interplay between the mechanical properties of double layer nano-beams and its magnetic properties. In your thesis project you will fabricate freely suspended nanostructures based on silicon nitride and ferromagnetic multi layers using state-of-the-art nano-lithography and metal deposition techniques. Further, you will probe the mechanical response of the nano-structures using optical interferometry while exciting the magnetization dynamics of the magnetic system. 

 

geeignet als

• Masterarbeit Physik der kondensierten Materie
• Masterarbeit Applied and Engineering Physics

Themensteller(in): Rudolf Gross

Transmons play the strings: Coupled mechanical and superconducting quantum circuits for probing vibrational modes and the transfer of quantum states

Circuit nano-electro mechanics is a new field in the overlap region between solid-state physics and quantum optics with the aim of probing quantum mechanics in macroscopic mechanical structures. We employ superconducting circuits to address fundamental questions like, the preparation of phonon number states in the vibrational mode and the conversion of quantum states between the mechanical element and the microwave domain. The initial successful experiments of the group include hybrid devices based on superconducting transmon qubits, microwave resonators and mechanical nano-string resonators. You should aim at the next, important step to integrate the nanomechanical string resonator into the transmon qubit to experimentally realize a new type of interaction in light matter coupling.

We are looking for a highly motivated master student joining this project. The goal of your thesis is the development of hybrid devices based on superconducting transmon qubits, nanomechanical string-resonators and superconducting microwave resonators as well as their spectroscopy. This includes the design and fabrication of these devices, where you will use state of the art simulation and nano-fabrication techniques. The second main aspect of your thesis is their investigation using highly sensitive microwave spectroscopy techniques in a low-temperature environment. 

geeignet als

• Masterarbeit Physik der kondensierten Materie
• Masterarbeit Applied and Engineering Physics

Themensteller(in): Hans-Gregor Hübl

Transmons play the strings: Coupled mechanical and superconducting quantum circuits for probing vibrational modes and the transfer of quantum states

Circuit nano-electro mechanics is a new field in the overlap region between solid-state physics and quantum optics with the aim of probing quantum mechanics in macroscopic mechanical structures. We employ superconducting circuits to address fundamental questions like, the preparation of phonon number states in the vibrational mode and the conversion of quantum states between the mechanical element and the microwave domain. The initial successful experiments of the group include hybrid devices based on superconducting transmon qubits, microwave resonators and mechanical nano-string resonators. You should aim at the next, important step to integrate the nanomechanical string resonator into the transmon qubit to experimentally realize a new type of interaction in light matter coupling. 

We are looking for a highly motivated master student joining this project. The goal of your thesis is the development of hybrid devices based on superconducting transmon qubits, nanomechanical string-resonators and superconducting microwave resonators as well as their spectroscopy. This includes the design and fabrication of these devices, where you will use state of the art simulation and nano-fabrication techniques. The second main aspect of your thesis is their investigation using highly sensitive microwave spectroscopy techniques in a low-temperature environment.

 

geeignet als

• Masterarbeit Physik der kondensierten Materie
• Masterarbeit Applied and Engineering Physics

Themensteller(in): Rudolf Gross